1. Field of the Invention
This invention relates to novel food compositions and food additives. The invention also concerns methods for preparing said food compositions.
2. Description of Related Art
It is generally known and accepted that one of the major risk factors for Coronary Heart Disease (CHD) is hypercholesteremia. Other risk factors are age and gender, smoking, diabetes mellitus, and hypertension.
Due to environmental factors and the huge spread of genetic heritage factors, it is difficult or even impossible directly to confirm a dependency between natural nutritional habits and the development of atherosclerosis which eventually leads to CHD. Therefore the relationship between cause and effect has had to be established based on a combination of pathophysiological, clinical and epidemiological studies into an associated chain of evidences. Hence, in epidemiological research a dependence between diet and serum lipid levels and composition, in clinical research a dependence between serum lipid levels and composition and coronary heart disease and in pathoanatomical research a dependence between coronary heart disease and arthritic atherosclerosis is confirmed. (Petri Kovanen, in Ravinnon rasvat ja kuidut suomalaisten terveyden kannalta, KELA julkaisuja ML:115, 1992, page 51). Hypercholesteremia is a major, if not even the biggest single, CHD factor.
Further, there exists a dependency between the risk factors of CHD and total cholesterol, the higher level of cholesterol, the higher risk of CHD (Framingham-study). In this respect it is not necessary to detail the individual lipoprotein dependence on CHD (negative or positive ingredients). However, population-wise a total cholesterol frequency and CHD risk factor curve may be drawn (Kalevi Pyörälä in Atherosclerosis VII, 1986 Proceedings, on page 42) Governmental Medical and Medicinal bodies issue drug-administrative guidelines for what percentile of this frequency curve should be offered drug therapy. CHD and atherosclerosis prevention by using modern hypocholesteremia drugs is a more than 10 Billion USD business and these medicines are among the best-selling drugs in the world. The most important cholesterol lowering drug are formed by statins (lovastatin, atorvastatin, simvastatin and fluvastatin), bilic acid sequestrants, nicotinic acid (niacin) and fibrates (bezafibrate and gemfibrozil).
The great majority of population suffering from or prone to incur hypercholesteremia take voluntary steps for lowering the cholesterol level while avoiding the direct use of the above mentioned drugs. These steps include physical exercises, nutritional aspects and cholesterol lowering functional food components (diets). Dietary ingredients proposed for lowering blood serum cholesterol include fat soluble plant stanol esters which can be added directly into food, plant sterols (non-esterified), phyllium which comprises soluble fibres, and tocotrienols extracted from palm oil.
The human cholesterol balance and metabolism is a delicate and complicated medical biochemical process which can essentially be divided into the interacting dependence between an enterohepatic and an exterohepatic circle (cf. Petri Kovanen in the KELA ML:115 book, p. 53). Most of the hypercholesteremia drugs, especially the above mentioned modern drugs like the statins, intervene with competitive inhibition at the committing rate limiting step in the enterohepatic circle in the formation of mevalonate, i.e. the HMG-COA reductase activity. This effect is called “endogenous cholesterol-depression” or “endogenous cholesterol inhibition”. The effect of these agents on the cholesterol level of the serum is strong. Intervention in and interference with the cholesterol balance by cholesterol-lowering functional food components is primarily carried out in the exterohepatic circle (in the following also called “exogenous cholesterol-depression or inhibition”). Examples of such food components are fibres, sitostanol esters etc.
Although the present dietary, cholesterol-lowering ingredients offer an interesting alternative for providing functional food components, there are some considerable limitations of their use. One of the most important limitations of the application of the commercial plant stanol esters and plant sterol mixtures (Benecol, Phytrol) is their poor solubility in other media than fats. For this reason, plant stanol esters and sterol mixtures are available only as margarine, salad dressings and candy bars.
Clearly, there is a need for a novel kind of food component which could be formulated into a functional food component and which would have a strong effect on the enterohepatic circle of the cholesterol balance. It should be noted that ingestion of plant sterol esters or sterol mixtures in at least 20–30 g daily doses in the form of margarines, salad dressings or candy bars is already an obesity risk factor for humans. And obesity per se is a risk factor for atheroma lesion formation and CHD.
By legend, the mushroom shiitake (Lentinula edodes) was the elixir of life for people in the Far East. In the 1960's and 1970's it was found that one of the particularly valuable components of shiitake was eritadenine, which is an aliphatic adenin and which is present in shiitake at concentrations of about 500 to 900 ppm.
Eritadenine is capable of reducing the concentration of cholesterol in blood serum (the Merck Index, 12th Edition, Merck & Co., Inc. NJ 1996, p. 624). Functional foods for lowering cholesterol concentration have been prepared by drying shiitake mushrooms, by pulverising the dried mushrooms and by extracting and concentrating the product to obtain an extract which can be mixed into food, such as gum, candy, soup etc., as disclosed in KR 9303886, Lotte Confectionary Co. DE Published Patent Application No. 3 531 482, Mori & Co. teaches a process for preparing a health-promoting foodstuff which contains as active ingredients soy bean lecithin and a powder of dried shiitake mushrooms.
As apparent from the above survey, the beneficial effect of eritadenine on the cholesterol level in serum is well-documented in the art. There are also some food products available which utilise this effect. In practice, the suggested foodstuffs are rather expensive and the demand for them is therefore limited. For many consumers drastic changes of dietary habits are difficult to implement and to continuously keep up. In view of the limited supply and narrow range of the modified food products, it would not even be possible for a consumer to completely change nutritional habits and, thus, to obtain a remedy for his increased serum cholesterol balance.
Further, it should be noted that many consumers (as well as the world of renowned international cuisines) find that food products containing animal fats, including cream, butter meat etc.) are more tasty than products solely or primarily containing vegetable fats. However, animal fats are also rich in saturated fats. The American Heart Association and the National Cholesterol Education Program gives the dietary guideline that no more than 8 to 10% of the day's calories should come from saturated fat and no more than 30% from fat overall. This means that animal fats should in practice entirely be avoided, since they generally contain over 50% saturated fat.
The present invention is based on the finding that the efficient reduction of the blood serum cholesterol level achieved by eritadenine, in particular d-eritadenine, is so strong that it will, even at low dosages, compensate for the cholesterol raising effect by animal fat products. In a prior study by Suzuki and Ohshima [Mushroom Science IX (Part I) Proceedings of the Ninth International Scientific Congress on the Cultivation of Edible Fungi, Tokyo 1974, 463–467], it was found that the serum cholesterol decreased when 60 g butter was taken together with 90 g of fresh shiitake mushrooms. The authors also suggests that shiitake be added to meals having large animal fats content such as sukiyaki and pork stew not only to improve the taste but also to help prevent or even cure hardening of the blood vessels.
The particular problem with using mushrooms as a source of eritadenine is that the concentration of eritadenine in the mushrooms is rather small. This means that the amount of mushrooms necessary for satisfying the human daily need is large (in excess of 500 g). Further, since the concentration is variable (500 to 900 ppm) and since it is not possible to standardize the shiitake production so as to provide a constant eritadenine content, it is impossible accurately to estimate and to adjust the added amount of eritadenine when mushrooms are used as a source of eritadenine.
Finally, it must be borne in mind that some people, approximately about 3% of the whole population, cannot eat mushrooms at all and about 20 to 30% of the population are allergic to mushrooms and especially to mushrooms in the unprepared form. This unavailability of unprepared mushrooms and their ingredients has to do with the very active and strong amino acidic and polysaccaridic complex composition which is fungus specific. A well-known fact is that mushrooms contain a lot of fibres, up to 50% of the dry matter, and one of the main fibre ingredients is chitin. Chitin in excessive amounts creates digestive problems in humans.